That's a sign of general stress. Mine do that when the temperatures are colder than the plants like, but lots of things could cause plant stress. It would help to know where the tomatoes are located, i.e., city/state/country.

All my sauce tomatoes did that last year - total crop failure. The slicers in another row were just fine.

If they are actually curling (the leaf tip rolls in toward the stem then it can either be exposure to herbicides from drift or contaminated mulch OR a disease. Would have to see a photo of them to know which.

However, if the leaves are really rolling rater than curling - the leaf sides cup/roll/fold up so they look like a taco shell - then it is stress. ID and eliminate the stress cause and the plants recover quickly.

Tomato leaf roll is common and often discussed here on the Tomato forum (lots of posts if you want to read them). The name of the condition is "Tomato Leaf Roll" and is defined at a physiological response of the plant to one of the stress factors such as excess water/rain, inconsistent soil moisture levels, pests such as aphids, whiteflies or thrips, over-fertilization, over-crowding, high winds, etc. etc.

Tomato Leaf Roll does not kill plants. It may reduce production because of the stress but the plants will survive and recover IF you eliminate the problem.

So to know which your friend has and how to correct it we'd need much more information about his growing conditions and a picture of the plant. Of you can Google 'tomato leaf roll' for pics to compare it to.

Hope this helps.

Dave

Thanks for the advice now mine are doing it too !! I've got nice big better boys but not a single tomatoe all of the blooms keep falling off ! I'm in northern OK . I probably overwater " every other day or so" But I only do that to try to keep regular so I don't get splits like last year thanks RJ

ke50zh:
The splits are caused from too much water.
It has been 90-100+ here in AZ and no watering for 2 days. I only water when the plants start to droop slightly. There is a spray you can buy "bloom set" for tomatoes. I think if you cut back on the water you may see an emprovement on leaves and blooms. Hope this helps
Arizona- hotter then africa hot

If it is overfertilization the cure is watering a lot, so you really have to think before you do anything.

It is occurring in one of my tomato plants (out of 8) the others are all happy. They are all in the same bed, and receive the same amount of water, fertilizer, sun etc. It is a different type (purple russian), so maybe it is just more sensitive to something. I am just crossing my fingers and hoping it will adjust. The weather has been so weird, almost 100 degrees for 2 days, then down to 60's with 45 degrees at night. But it seems to have stabilized now.

I too have the same problem and many other too.. some of my tomatoes got rotten when it was still green...I had put some egg shells under it.. now a tomato started to ripe....but the upper leaves of the plant is curling up...and now no new tomatoes are coming on my plant in the picture...another tomato plant had grown by itself in my flower bed but now that too started to curl what should I do? I water it once in two days and I live in the middle east..now the climate is not too hot but not even cold..

this is the one that popped out in my flower bed...there are tomatoes coming up in this one...but the leaves started to curl from today onwards..

Check for spider mites.. My plants last year had the same problem and I figured out the damn spiders string a web and pulls the leaf so it lookes "curled".. I just squished the tiny spiders and sprayed with water and it was fine.. Although my plants didn't have discolored leaves, it could be several problems..

Joe

qibu, your tomato leave are showing signs of nutrient deficiency. It looks like zinc deficiency, or iron. Please google tomato leave margin yellowing.